1. Field of Invention
The present invention relates to a channel controller for magnetic disks used as data storage means for large computers and similar data processing devices, and more particularly, to a controller for a magnetic disk comprising a plurality of double-sided platters.
2. Description of the Prior Art
Presently, most large and medium size computers use magnetic disks for data and program storage. Originally disks having only one active storage and retrieval surface have been used for mini and microcomputers, while for larger computer disks having several storage surfaces are used, each face being accessed by dedicated read/write heads. Data (or programming instructions) are read and written by directing a respective head to the location on a particular surface where the particular binary signals can be saved or retrieved. Thus data may be written or read through several heads sequentially. Of course, this type of data storage systems requires a rather complex controller for directing the heads and reading and writing data efficiently in the correct sequence. All the known prior art channel controllers were machines which incorporated a microprocessor for the channel and another one for the controller, which generate controls based on sequential microcodes stored in the microprocessor random access memory. It was found that these machines do not perform fast enough for the present day computers, and their complex architecture impairs the channel-controllers' reliability. (Mostly because of too many communication between channel and the controller).